IME best predictor of "success" is the prestige/brand of the candidates have before they entered the program. It's based on candidate selection, not ability. But with the VC model there is pressure to grow, so they lower the bar and accept people who aren't transitioning from prestige background; PHD's/name brand schools or companies... and shocker they struggle to find a job.

They are scams because they juke the stats. They hire their own graduates to up placement rates & deceptively determine there own exclusion criteria to remove data of people who didn't get placed.